Just because a bird hasn’t been seen for more than a hundred years doesn’t mean it’s extinct. That’s the thought behind BirdLife International’s new search to confirm the existence of 47 bird species unseen for up to 184 years.

“History has shown us that we shouldn’t give up on species that are feared to have gone to their graves,” said Marco Lambertini, BirdLife International’s chief executive, in a press release.

He cites the Cebu flowerpecker as a prime example. Scientists believed this bird—a swallow-sized black, red and white species endemic to the small Philippine island from which it gets its name—went extinct in the early 20th century due to habitat destruction. But it was rediscovered in 1992, and has been seen as recently as 2007.

“The story of Cebu flowerpecker is living proof that by focusing our efforts and resources, we really can make positive difference for the world’s biodiversity,” said Tim Appleton, co-organizer of the British Birdwatching Fair, where BirdLife announced its quest.